Charging a portable electrical device

ABSTRACT

A portable electrical device requiring periodic recharging mates with a corresponding charging device by dropping or placing the portable device on or in the charger without pre-alignment by the user. The charger-to-device interface self aligns the portable electrical device in the charger for charging. Preferably, the charger is a bowl-shaped cradle. The portable device sinks to the bottom of the bowl using the force of gravity and thus aligns the contacts for recharging. Optional magnets may provide additional force to guide alignment.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application of pending U.S. patent application Ser.No. 12/351,892, filed Jan. 12, 2009, entitled “Charging a PortableElectrical Device”, which is a divisional application of U.S. patentapplication Ser. No. 11/132,657, filed May 19, 2005, entitled “Methodand Apparatus for Charging a Portable Electrical Device”, now issued asU.S. Pat. No. 7,477,039, both of which are herein incorporated byreference. This application claims priority under 35 U.S.C. §120 of U.S.patent application Ser. No. 12/351,892, filed Jan. 12, 2009, and of U.S.patent application Ser. No. 11/132,657, filed May 19, 2005.

The present application also related to the following commonly assigneddesign patent applications, both of which are incorporated by reference:

Application Ser. No. 29/213,910, filed Sep. 23, 2004, entitled “PortableDigital Audio Player”, now issued as U.S. Design Pat. D 514,122; and

Application Serial No. 29/215,158, filed Oct. 14, 2004, entitled“Charging Bowl for Portable Digital Audio Player”, now issued as U.S.Design Pat. D 527,704.

FIELD OF THE INVENTION

The present invention relates to portable electrical devices, and inparticular, to a charging interface for charging a stored energy sourcewithin a portable electrical device.

BACKGROUND OF THE INVENTION

In the latter half of the twentieth century, there began a phenomenonknown as the information revolution. The information revolution is ahistorical development broader in scope than any one event or machine,and while often associated with large general-purpose computers, it hasoften found expression in much smaller devices. In fact, one of theremarkable aspects of the information revolution is how digitalelectronic processors are used to enhance the capabilities of otherdevices, from automobiles to refrigerators.

The information revolution has spawned a large variety of portableelectrical devices. Specifically, the expanding capabilities andshrinking physical size of digital electronic devices have encouragedthe development of portable devices. This phenomenon has made itpossible, for example, for anyone to walk into an electronics store andpurchase a laptop computer which is far faster and more capable than themost advanced and expensive computing systems of the 1950s, systemswhich might have occupied entire floors of buildings. Because it is nowpossible to place powerful processing capability in a single chip on arelatively small device, new uses have been created and are beingcreated for portable devices with digital processing capability.Examples of such portable devices include cell and cordless telephones,personal digital assistants (PDAs), music and video players, laptopcomputers, and a wide range of sensing, testing and diagnostic devicesfor medical, environmental, or industrial purposes.

Although some devices are considered “portable” simply because they canbe moved from place to place, of particular interest herein are thoseportable electrical devices which contain their own source of storedelectrical energy (e.g. batteries), and are therefore not dependent onthe proximity of an external source of electrical power. The informationrevolution has caused many new and varied types of such portableelectrical devices to be used, but it must be remembered thatbattery-operated portable electrical devices have been around for a longtime, and do not necessarily require digital data processing capability.For example, battery operated power tools, toys, flashlights and soforth have been in use for many years, and continue to be used.

Many portable electrical devices, especially digital electronic devices,contain rechargeable batteries. In some cases, these rechargeablebatteries are recharged by removing them from the portable device,placing them in a special purpose charging device (usually connected toa line voltage source) until the electrical charge is sufficientlyreplenished, and then re-installing the batteries in the portabledevice. This method has obvious disadvantages from the standpoint ofconvenience to the user, and also introduces the possibility that theuser will place the batteries in the charger in an erroneousorientation, re-install the batteries in the device in an erroneousorientation, or in some other manner cause damage to the batteriesand/or the electrical device during the process of recharging thebatteries. In order to reduce these hazards and make recharging moreconvenient, many portable electrical devices are design to be coupleddirectly to a charging device or voltage, without requiring removal ofthe batteries. This mode of recharging is particularly common in thecase of cell and portable telephones, which require frequent recharging.

If a portable device having rechargeable batteries is coupled to acharging device (without removal of the batteries), coupling istypically accomplished by either mating an electrical plug connected bycable to either the charger or the device with a correspondingreceptacle, or by placing the portable device in a cradle formed by thecharging device so that electrical contacts align. In some cases, theportable device is plugged directly into a line voltage receptacle, theportable device containing all the electronics required for transformingand rectifying a line voltage signal.

Although any of these techniques is generally more convenient thanremoval of the batteries for recharging, and is less likely to causedamage to the device and/or batteries, these techniques still require acertain level of attention and interaction on the part of the user.I.e., the user must visually or otherwise align certain matingcomponents to a relatively narrow degree, and place the matingcomponents in proper relative position.

While the burden of visually or otherwise aligning a portable electricaldevice with respect to its corresponding charging device and placing thetwo in proper position may seem like a small matter, it can causeinconvenience in a variety of ways, particularly as the number of suchportable devices increases. For example, it may be difficult to couplethe portable device to the charger while performing some other taskrequiring visual concentration; the need for visual alignment usuallylimits the acceptable locations of charging devices to those locationshaving ample light and at the proper height for convenient visualalignment; certain individuals with physical handicaps may find itparticularly difficult; etc. As a particular example, a user may wish tocouple a portable device to a recharging device while performing anothercomplex task, such as driving an automobile. A need exists, notnecessarily generally recognized, for an improved interface between aportable electrical device and its charging device, which will requireless attention and interaction on the part of the user.

SUMMARY OF THE INVENTION

A portable electrical device requiring periodic recharging mates with acorresponding charging device by dropping or placing the portable deviceon or in the charger without pre-alignment by the user. Thecharger-to-device interface self aligns the portable electrical devicein the charger for charging.

In one aspect of the preferred embodiment, the charger is a concavecradle which is open at the top. The portable device is placed ordropped in the cradle, and sinks to an aligned position at the bottom ofthe cradle using the force of gravity.

In another aspect of the preferred embodiment, the mating surfaces ofthe charger and portable device are radially symmetrical about avertical axis. When the portable device is placed in or on the charger,the device is either aligned with respect to the charger at anyarbitrary angular orientation, or aligned at a plurality of discreteangular orientations, the charger and device automatically self-aligningto one of the plurality of discrete angular orientations.

In a specific preferred embodiment, the charger forms a bowl-shapedconcave cradle having a cross-section in the horizontal plane which iscircular about a substantially vertical axis. The portable device has asurface conforming to the bowl-shaped cradle. A pair of electricalcontact rings, concentric about the vertical axis, is embedded in thesurface of the cradle. The contours of the cradle and device causegravity to force the device to the bottom of the cradle where the devicewill mate electrically with the charger, regardless of the angularorientation of the portable device with respect to the vertical axis.

Various alternative shapes for the mating surfaces of the charger andportable device are possible, such as shapes in which a horizontalcross-section of a mating surface is a regular polygon, a star, anellipse, or any of various other shaves. Furthermore, the charger neednot have a concave mating surface, nor must the mating surfaces beradially symmetrical.

In an additional aspect of the preferred embodiment, magnets may beplaced in the charger and/or portable device to provide additionalalignment force.

A charging interface for a rechargeable portable electrical device inaccordance with the preferred embodiment of the present inventionrequires less concentration, visibility and/or dexterity thanconventional charging interfaces. It is not only easier to use, butincreases the flexibility in the way or location in which such a deviceis used. A bowl-shaped charger can be analogized to a small bowl or trayin which keys or similar objects are routinely placed. A user can placea portable device in the charger with a minimal amount of effort anduser attention immediately upon entering his abode or while driving hiscar, at a time when the user is likely to be distracted with othertasks, carrying other objects, and so forth. Moreover, the charger canbe located almost anywhere within arms reach, even if the location(e.g., a high shelf, under an instrument panel of a vehicle, etc.) issuch that the user can not visually guide the alignment. Additionally,persons with certain physical handicaps may find such a charginginterface significantly easier to use.

The details of the present invention, both as to its structure andoperation, can best be understood in reference to the accompanyingdrawings, in which like reference numerals refer to like parts, and inwhich:

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a simplified perspective view showing a the major componentsof a charging interface for a portable electrical device, according tothe preferred embodiment.

FIG. 2 is a top plan view of a charging device for a portable electricaldevice, according to the preferred embodiment.

FIG. 3 is a simplified sectional view of the charging device of FIG. 2in the plane of the central axis, according to the preferred embodiment.

FIG. 4 is a simplified front plan view of a digital music player as anexemplary portable electrical device, according to the preferredembodiment.

FIG. 5 is a simplified rear plan view of the exemplary portableelectrical device, according to the preferred embodiment.

FIG. 6 is a simplified sectional view of the exemplary portableelectrical device in the plane of the central axis, according to thepreferred embodiment.

FIGS. 7A and 7B are cross-sectional views representing the positioningof the portable electrical device in the charging device for recharging,FIG. 7A showing an initial placement of the portable device in anunaligned position, and FIG. 7B showing the final resting place of theportable device in an aligned position, according to the preferredembodiment.

FIG. 8 is an enlarged sectional view of a portion of a contact,according to the preferred embodiment.

FIG. 9 is a simplified top plan view of a charging device and portableelectrical device having a square horizontal cross-section, the devicesbeing in recharging position, according to an alternative embodiment ofthe present invention.

FIG. 10 is a simplified sectional view in the plane of the central axisof a charging device and portable electrical device in rechargingposition, according to the alternative embodiment of FIG. 9.

FIG. 11 is a simplified top plan view of a charging device and portableelectrical device having an elliptical horizontal cross-section, thedevices being in recharging position, according to a second alternativeembodiment of the present invention.

FIG. 12 is a simplified sectional view in the plane of the central axisof a charging device and portable electrical device in rechargingposition, according to the second alternative embodiment of FIG. 11.

FIG. 13 is a simplified sectional view in the plane of the central axisof a charging device and portable electrical device in rechargingposition, according to a third alternative embodiment.

FIG. 14 is a simplified rear plan view of the a portable electricaldevice in which charging contacts are configured according to analternative embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention described herein relates to an interface for mating aportable electrical device requiring periodic recharging with a chargingdevice providing electrical energy to the portable electrical device.Both the portable electrical device and the charging device must beconstructed so as to be compatible with each other, i.e., to haveappropriate mating surfaces, appropriately located electrical contactsor other features for the transmission of electrical energy from thecharging device to the portable electrical device, and so forth.Therefore, in the preferred and certain alternative embodimentsdescribed herein, a pair of devices (the portable device and thecharging device) are shown and described. However, the claims herein donot necessarily require the presence of a pair of compatible devices,and either one of the devices alone may infringe certain of the claimsherein.

Referring to the Drawing, wherein like numbers denote like partsthroughout the several views, FIG. 1 is a perspective view showing a themajor components of a charging interface for a portable electricaldevice, according to the preferred embodiment. FIG. 1 represents theoutlines of a charging device 101 and corresponding portablerechargeable electrical device 102 to which charging device 101 supplieselectrical charging energy. For clarity of illustration, certaindecorative and functional features of devices 101 and 102 are not shownin FIG. 1. Charging device 101, herein also referred to as a “chargingbowl”, is a generally bowl-shaped device, having an upwardly exposedconcave surface. Portable rechargeable device 102 is a generallydiscus-shaped device, which rests within charging bowl 101 during arecharging operation. At least a portion of the rear surface of portablecharging device 102 opposes and conforms generally to a correspondingportion of the upwardly exposed concave surface of charging bowl 101.Electrical contact areas 103, 104 of opposing polarity are situated onthe conforming opposed surfaces of charging bowl 101 and portablecharging device 102. In the preferred embodiment, the contact areascomprise a circular contact 104 and a concentric ring 103, both beingcentered about a common axis, which is the central axis of both thecharging bowl 101 and the disk-shaped portable device 102. Contact areas103, 104, are located underneath rechargeable device 102, and thereforerepresented as dashed lines in FIG. 1.

It will be observed that the contacts on the opposed surfaces are inproper position with respect to one another and mate with thecorresponding contacts in the other device provided only that theportable device is resting at the bottom of the charging bowl. In thisposition, the central axes of the charging bowl and of the portabledevice are substantially coincident. Specifically, because the contactsare circles and concentric rings, the contacts mate in properorientation, regardless of the angular orientation of the portabledevice with respect to the central axis. Gravity and/or a magnetic forcenaturally forces the portable device to this aligned position when it isdropped or placed anywhere within the bowl, without the need for theuser to pre-align the portable device.

FIGS. 2 and 3 are respectively a simplified top plan view and simplifiedcross sectional view in a vertical plane of charging device 101,according to the preferred embodiment. Charging bowl 101 is a generallybowl-shaped device, having a base 301 for resting on a horizontalsurface and an upwardly exposed concave surface 201 for receiving andmating with a portable rechargeable device. The mating surface ispreferably radially symmetrical about a central substantially verticalaxis, the vertical axis being perpendicular to the plane of FIG. 1. FIG.2 is a cross section in the plane of the vertical axis. A cross sectionof mating surface 201 in a horizontal plane (perpendicular to thevertical axis) is a circle centered at the vertical axis.

FIGS. 4, 5 and 6 are respectively a simplified front plan view,simplified rear plan view, and simplified cross sectional view in avertical plane of portable electrical device 102, according to thepreferred embodiment. In this embodiment, portable electrical device 102is a portable digital music player which is generally in the shape of adisc, and having a central axis. The planes of FIGS. 4 and 5 areperpendicular to the central axis, while FIG. 6 is a cross section in aplane of the central axis. In this embodiment, the cross section in aplane of the central axis is generally an elongated oval shapeapproximating an elongated ellipse, the profile of the front face beingsubstantially symmetrical to the profile of the rear face, although suchsymmetry is not a functional requirement. Although the basic outlines ofdevice 102 define a disc, various functional features are present whichdefeat perfect radial symmetry. The front face 401 of device 102contains features of a user interface enabling a user to control thedevice. As shown in FIG. 4, the front face includes a visual display 402for displaying information to the user, and various control buttons403A-D for receiving user input. A headphone jack 404 and thumbwheelcontrol 405 (e.g., for volume) are located along the circumferentialedge of the discus. The rear face 501 includes a mating surface whichmates with corresponding mating portion of charging bowl surface 201.The mating surface of rear face 501 is generally radially symmetricalabout the central axis, conforming to the corresponding mating surfaceof the bowl. Specifically, a cross section of the rear face in a placeperpendicular to the central axis defines a circle.

A pair of electrical contacts 202, 203 of opposite polarity is embeddedin charging bowl surface 201. The contacts mate with correspondingcontacts 502, 503 of opposite polarity in the corresponding matingsurface of rear face 501 on the portable device to provide a chargingcurrent to the portable device when the portable device is properlypositioned within the charging bowl, i.e., is positioned so that thecentral axis of the portable device is substantially coincident with thevertical axis of the charging bowl. In the preferred embodiment,contacts 203 and 503 are in the shape of a circle, and contacts 202 and502 are in the shape of a ring surrounding respective contacts 203 and503, although other shapes are possible. Both contacts 202 and 203 arecentered on the vertical axis of the charging bowl; both contacts 502and 503 are centered on the central axis of the portable device.

In will be understood that in the simplified views of FIGS. 2-6, certainfeatures not essential to an understanding of the present invention havebeen omitted for clarity. In particular, the digital music playercontains electronic elements mounted in the interior thereof as requiredto perform the device function, and the charging bowl similarly containsinterior electronic elements. These devices may further containdecorative features, status indicator lights, and additional exteriorelements not visible in the simplified representations of FIGS. 2-6.

In operation, the user engages the charging device by placing ordropping the portable device in the charging bowl. The portable devicesinks to the bottom of the bowl by force of gravity, or optionally, withan additional force of magnetic attraction. The portable device need notbe placed in the center of the bowl, but can be placed anywhere withinthe bowl. In particular, the user need not align contacts 502, 503 inthe portable device with corresponding contacts 202, 203 in the chargingdevice when placing the portable device in the charging bowl. It couldeven be placed on the edge of the bowl, with a portion of the portabledevice extending out of the bowl, provided that the device's center ofgravity is within the bowl's edge. The portable device need not have anyparticular angular orientation with respect to the bowl. The centralaxis of the portable device upon placement in the bowl need not bevertically oriented, and can be at an oblique angle, provided that theorientation and center of gravity of the portable device will cause itto rotate its rear face 501 to face downward. as it drops to the bottomof the bowl. In the preferred embodiment, contacts 502, 503 are locatedonly on the rear face 501 of the portable device, requiring the user toat least assure that the device is placed in the bowl so that the rearface will face downward. It would alternatively be possible to placecontacts on both front and rear faces, obviating this requirement.

The positioning of the portable device in the bowl is represented inFIGS. 7A and 7B. FIG. 7A is a cross sectional representation of theportable device initially placed in the charging bowl in an unalignedposition, i.e., in a position in which contacts 502, 503 in the portabledevice are not aligned with corresponding contacts 202, 203 in the bowl.In this unaligned position, a gravitational force (optionally assistedby a magnetic force) draws the portable device in the direction shown bythe arrow in FIG. 7A. The gravitational force (and optional magneticforce) eventually cause the portable device to rest at the bottom of thecharging bowl, in the position shown in FIG. 7B. In this position, thecentral (vertical) axis of the charging bowl and the central axis of theportable device are substantially coincident, and the contacts arealigned. It will be noted that, because the contacts are either circularor annular, the contacts are aligned regardless of the angularorientation of the charging device with respect to the bowl about thecentral axis. The portable device can assume any arbitrary angularorientation about the central axis.

Preferably, contacts 202, 203 are spring loaded to exert a force againstthe surface of mating contacts on the portable device when the portabledevice is in charging position. FIG. 8 is an enlarged view of a portionof contact 202. As shown in FIG. 8, contact 202 comprises a solid metalconductor 801 in the shape of a ring (shown in partial cross-section inFIG. 8), which is supported by a spring 802. Spring 802 could beconstructed as multiple circumferentially spaced helical springs (one ofwhich is represented in FIG. 8), or with beam springs, conical springs,or any of various types of springs as are known. A flange 803 on thering 801 engages the walls of the charging bowl's surface. When theportable device is not present, the springs force the flange to abut thewalls of the bowl, causing the contact to project slightly from matingsurface 201. The weight of the portable device depresses the contacts sothat the springs force the two contact surfaces together. The contactsare rounded at the projecting edges to allow the portable device toslide freely over them when initially assuming the charging position.Although only contact 202 is illustrated in FIG. 8, it will beappreciated that a spring loading mechanism can be similarly constructedfor contact 203. In the preferred embodiment, only the bowl contacts arespring loaded, the contacts on the portable device being fixed withrespect to the device's surface. It would alternatively be possible toconstruct the portable device with spring loaded contacts, although thisapproach is not preferred because it adds weight and complexity to theportable device, and may subject the spring-loading mechanism to damagefrom frequent handling. It alternatively may be possible to foregospring loading altogether any rely on gravitational or other forces toachieve sufficient contact.

As described above, both sets of contacts form circles and concentricrings according to the preferred embodiment, this arrangement providingelectrical contact between the two devices regardless of the angularorientation of the portable device with respect to the charging bowl.However, there are alternative configurations of contacts which willalso provide contact an any arbitrary angular orientation. Inparticular, if only one of the charging bowl or the portable devicecontains a ring, the other device may contain a much smaller contact (ormultiple smaller contacts) located at the same radial distance from thecentral axis as the ring. In this case, since the ring is continuous,the smaller contact or contacts will engage the ring at any arbitraryangular orientation of the portable device, so long as the central axisof the portable device is substantially coincident with the central axisof the charging bowl. FIG. 14 illustrates such an alternativearrangement of contacts on the rear surface of a portable rechargeabledevice 1401, which is similar to portable device 102 except for thearrangement of contacts. In this alternative embodiment, contacts 1402,1403 engage bowl contacts 202, 203 respectively. Although contact 1402is only an off-center circular contact, because contact 202 is annular,it will engage contact 202 regardless of the angular orientation ofdevice 1401. Of course, it would also have been possible to maintain thesame contact geometry in the portable device, and use the geometry ofFIG. 14 in the charging bowl contacts. Additional variations in contactgeometry are possible.

Depending on the design of the charging bowl and portable deviceinterface, it is possible that gravitational force alone will not bereliably sufficient to position the portable device at the bottom of thecharging bowl, with its contacts centered on the vertical axis of thebowl. As the portable device approaches the bottom of the bowl, theangle of the inclined surface on which it rests decreases, reducing thegravitational force. At some point, frictional forces of the contactingsurfaces may cause the portable device to come to rest at a positionslightly short of the bottom of the charging bowl. If the shapes of themating surfaces and coefficients of friction are such that thegravitational force alone is insufficient to reliably align the contactson the devices, an optional additional alignment force may be provided.Preferably, this additional alignment force is provided by optionalmagnet 302 placed within the charging device, and located at the bottomof the bowl surface 201, as shown in FIG. 3. Magnet 302 exerts anattractive force on a complementary magnet 601 or ferromagnetic material(as shown in FIG. 6) in the portable device, thus providing additionalforce (i.e., beyond gravitational force) to position the portable deviceso that it is centered at the bottom of the bowl. Although magnets 302,601 are represented in the Figures as located behind respective circularcontacts 203, 503, as a further alternative, one or both devices maycontain an annular ring in place of the circular contact. I.e., insteadof a ring contact 202 or 502 surrounding a central circular contact 203or 503, a device could contain a pair of concentric annular rings, theinner ring having an inner radius sufficiently large to accommodatemagnet 302 or 601. Such an arrangement may be desirable because itbrings the magnets into greater proximity with each other, thusincreasing the attractive force. exerted on the portable device. Theremay be other techniques for providing an additional alignment force.

Charging bowl receives electrical energy from an external source (notshown), from which it provides charging current to the portable device.The current provided to the portable device is preferably a DC currenthaving a voltage compatible with the batteries in the portable device.Electrical energy is preferably obtained from a line voltage, whichtypically means it must be transformed to a lower voltage and rectifiedbefore being supplied to the portable device. Power conversionelectronics for performing the required transformation and rectificationmay be located within charging bowl 100, or in an external powerconversion device, or may partially located within charging bowl 100 andpartially in an external power conversion device. Alternatively, it ispossible to locate some of the power conversion electronics within theportable device itself, although this is generally not preferred becauseit tends to increase the size and/or weight of the portable device, andbecause the charging interface should be at a low voltage for safetyreasons.

It will be observed that, due to the radial arrangement of the contacts,if the portable device is initially placed at the edge of the chargingbowl and allowed to slide downwards to the bottom of the bowl, first theouter ring contact 502 and then the center contact 503 will bridgebetween the two contacts 202, 203 on the charging bowl. Normally, thiswill cause only a momentary electrical short between the contacts on thecharging bowl as the portable device travels to the aligned position,although in unusual circumstances the portable device may become stoppedin a shorted position. For these reasons, it is preferred that the powerconversion electronics contains protection against such circumstances,either as an inherent part of its design or by use of some form ofprotection circuit. Various forms of protection circuits are known inthe art, and any such circuit, now known or hereafter developed, may beemployed. Perhaps the simplest form of protection is a current limitingcircuit which limits the maximum charging current provided to chargingdevice to some safe, relatively small value. Other, more sophisticated,forms of short protection are possible, such as short detection circuitswhich would automatically switch the charging current off upon detectinga contact-to-contact resistance below some small value. For similarreasons, some form of protection may be necessary in the portable deviceto prevent discharging a battery when one of the contacts of thecharging device shorts the contacts of the portable device. In thislatter case, it is only necessary to protect current flowing backwardthrough the contacts, (i.e., the reverse of normal current flow duringrecharging). Therefore a series diode at the contact should besufficient to prevent discharge, although other forms of protectionmight alternatively be used.

Alternative Mating Surface Configuration Examples

The mating surface configuration of the preferred embodiment, describedabove and represented in FIGS. 1-6, is but one possible embodiment ofthe present invention. Numerous alternative configurations of thedevices and mating surfaces are possible. Some of these alternativeconfigurations are described below and represented in FIGS. 9-13. Itshould be understood that these alternative configurations are shown anddescribed by way of illustration and not by limitation, and are notintended as an exhaustive enumeration of all possible alternativeconfigurations consistent with the present invention.

In the preferred embodiment, the mating surfaces define a circle in aplane perpendicular to the central or vertical axes. A circle is perhapsthe simplest implementation of the present invention, although by nomeans the only such implementation. A mating surface might alternativelydefine any of various shapes in a plane perpendicular to the central orvertical axes, which may or may not be symmetrical about the axes. Suchalternative shapes may be employed for a variety of functional and/oraesthetic reasons. By way of example, such alternative shapes mayinclude regular polygons, star shapes, and ellipses or other elongated,rounded shapes.

FIGS. 9 and 10 are respectively a top plan view and a sectional view inthe central axis of a charging device 901 and portable device 902,according to an alternative embodiment of the present invention. FIGS. 9and 10 show the two device in an aligned position for recharging theportable device. In this alternative embodiment, the mating surfacesdefine a regular polygon, specifically a square, in the planeperpendicular to the central axis. It will be understood that as afurther alternative, the mating surfaces could define a regular polygonhaving a number of sides other than four, and/or that the corners mayhave radiuses.

In the alternative embodiment of FIGS. 9 and 10, the contacts are acentral square 904 and a hollowed square-shaped region 903 surroundingthe central square. It will be observed that these contacts are notaligned at any arbitrary angular orientation of the portable device 902with respect to the charging device 901, but are aligned only when theflat sides of the mating surfaces coincide. I.e., alignment occurs onlyat any of four discrete angular positions of the portable device withrespect to the charging device about the central axis. Although theportable device must be aligned to one of these four discrete positionsfor recharging, no pre-alignment is required by the user. As in the caseof the circular mating surface of the preferred embodiment, the usersimply drops or places the portable device in the charging bowl at anyarbitrary angular position. The force of gravity (optionally assisted bymagnets) causes the portable device to rotate about its central axis toone of the four aligned positions at the same time that is sinks to thebottom of the charging bowl.

FIGS. 11 and 12 are respectively a top plan view and a sectional view inthe central axis of a charging device 1101 and portable device 1102,according to a second alternative embodiment of the present invention.FIGS. 11 and 12 show the two device in an aligned position forrecharging the portable device. In this second alternative embodiment,the mating surfaces define an elongated curved figure, specifically anellipse, in the plane perpendicular to the central axis. It will beunderstood that as a further alternative, the mating surfaces coulddefine some other form of elongated curved figure, or could define anelongated polygon which generally follows the outlines of an ellipse orsimilar oval figure, which may or may not have radiuses at the cornersthereof.

In the alternative embodiment of FIGS. 11 and 12, the contacts are acentral filled ellipse 1104 and a hollowed annular elliptical region1103 surrounding the central ellipse. As in the case of the squareembodiment of FIGS. 9 and 10, these contacts are not aligned at anyarbitrary angular orientation of the portable device 1102 with respectto the charging device 1101, but are aligned only when the line segmentsdefined by the focal points of the ellipses are substantially parallel,i.e., alignment occurs at only two discrete angular positions ofportable device 1102 with respect to charging device 1101 about thecentral axis. As in the case of the embodiment of FIGS. 9 and 10, nopre-alignment is required by the user. The user drops or places portabledevice 1102 in the charging bowl at any arbitrary angular position. Theforce of gravity (optionally assisted by magnets) causes the portabledevice to rotate about its central axis to one of the two alignedpositions at the same time that is sinks to the bottom of the chargingbowl.

The mating surface configuration of the preferred embodiment is anelongated, rounded surface in the plane of the vertical or central axes,in which the dimension of the portable device in a direction parallel tothe central axis is significantly shorter than in a directionperpendicular to the central axis, so that the mating surface is arounded, flattened portion of the portable device. However, it wouldalternatively be possible to construct the portable device with a longerdimension parallel to the central axis, and a shorter dimensionperpendicular to the axis. Such an alternative embodiment is illustratedin FIG. 13.

FIG. 13 is a simplified cross-section in the plane of the central axis,showing a charging device 1301 and portable electrical device 1302,according to a third alternative embodiment. In this embodiment, it maybe assumed that the charging device and portable electrical device areradially symmetrical about the central axes thereof, and specifically,that a cross-section of the mating surface in a plane perpendicular tothe central axis defines a circle, as in the preferred embodiment(although other shapes are possible, as explained above). However,unlike the previous embodiments, the dimension of the portable deviceparallel to the central axis is substantially longer than the dimensionperpendicular to the axis. The shape of the portable device thereforemore nearly resembles a sausage than a saucer. The charging device isaccordingly provided with a relatively deep bowl or well, into which thenarrow end of the sausage-shaped portable device is dropped.

Although FIGS. 9 and 10 show an alternative mating surface configurationwhich is aligned in four discrete angular positions about the centralaxis, and FIGS. 11 and 12 show an alternative configuration with isaligned in two discrete angular positions about the central axis, itwould be possible to design configuration aligning in a different numberof discrete angular positions. Furthermore, it would be possible todesign mating surface configurations which are not symmetrical about acentral axis, and/or which align in only a single angular position ofthe portable device, using a force of gravity and/or some other force,such as a magnetic force. A simple example of a device which aligns atonly a single angular position is a device having a circular horizontalcross-section (as in the preferred embodiment), but having one or moreoffset magnets for rotating the portable device to a particular desiredangular position. Alternatively, the mating surfaces themselves can bedesigned to rotate the portable device to a desired single angularposition using gravity, in which case the mating surfaces arenecessarily not radially symmetrical. An example of such a matingsurface is a shape defined by an inverted cone intersected by a plane atan oblique angle to the central axis of the cone. It will be appreciatedthat numerous other shapes are possible.

All of the configurations shown in the various figures employ agenerally concave charging bowl surface and convex charging surface onthe rechargeable device. However, it would alternatively be possible forthe charging device to have a convex surface and the rechargeable deviceto have a concave surface.

Various alternative mating surface shapes have been disclosed herein inorder to express a small sample of the possible range of alternatives.In general, the saucer shape of the preferred embodiment is believed tobe simplest from the standpoint of assuring proper alignment under awide range of uses. However, there may well be other considerations onthe design of a portable electrical device which suggest another shape.For example, if the portable electrical device is a cell phone, it isgenerally considered desirable that the device be elongated to bridge atleast part of the space between the user's mouth and ear. In this case,it may be desirable to use a shape similar to one of those shown inFIGS. 11-12 or FIG. 13.

Further Alternative Embodiments and Implementations

In the exemplary implementation described above, the portable electricaldevice is a digital audio player. However, it will be appreciated that awide variety of portable rechargeable electrical devices exist to whichthe present invention might be applied, some of which have beenspecifically mentioned herein. The present invention is not limited todigital audio players or any other examples specifically discussedherein, and further is not limited to devices of the type currentlyknown or contemplated. Just as personal digital assistants and manyother devices were unknown until relatively recently, it is anticipatedthat, with further progress in the electrical arts, new portableelectrical devices, now unknown, will be developed. The presentinvention may provide a useful charging interface appropriate for atleast some of these new portable electrical devices.

In the implementations described above, it has generally been assumedthat the base of the charger rests on a flat surface such as a shelf,but the charger might alternatively be mounted by mechanical means to avertical wall or other member. In particular, where used in a motorvehicle, the charger would preferably be firmly attached to some portionof the vehicle. In any such application, the charger might be mounted ona retractable apparatus.

In the above description, it has generally been assumed that theportable electrical device stores energy in “batteries”, which areperiodically recharged. Conventionally, batteries are chemical cells inwhich energy is stored in chemical form, from which it is converted toelectrical energy. However, the present invention is not limited to anyparticular form of energy storage, and a portable, rechargeable devicecould use any appropriate form of stored energy, now known or hereafterdeveloped. For example, it is possible to store electrical energy in acapacitor, and while conventional capacitors are generally inferior tochemical batteries for providing electrical energy to portable musicplayers and similar devices, future improvements to capacitors or otherdevices may make their use for powering portable devices more desirable.

In the above description, it has been assumed than an electrical currentpasses between the charging device and the portable device by means of“contacts”. While this is the most common method of supplying electricalenergy to a rechargeable electrical device, it is not necessarily theonly such means. It is alternatively possible to supply electricalenergy for recharging the portable device by induction through anelectromagnetic field, without the actual passage of current between thedevices. However, even in this case it is generally necessary to alignthe portable device with respect to the charging device, and the presentinvention could be applied to a charger which induces a current in theportable device when the latter is in an aligned position in a bowl orequivalent charging structure.

Although a specific embodiment of the invention has been disclosed alongwith certain alternatives, it will be recognized by those skilled in theart that additional variations in form and detail may be made within thescope of the following claims:

1. An apparatus, comprising: at least one device from a set of devicesconsisting of: (a) a portable electrical device capable of storingelectrical energy and requiring periodic recharging, and (b) a chargingdevice for supplying electrical energy to said portable electricaldevice during recharging thereof; wherein said portable electricaldevice and said charging device comprise respective complementary matingsurfaces which transmit electrical energy from said charging device tosaid portable electrical device during recharging of said portableelectrical device, each said mating surface having a respective firstplane of symmetry bisecting the mating surface, the mating surface beingsymmetrical about the respective first plane of symmetry, and arespective second plane of symmetry bisecting the mating surface andperpendicular to the respective first plane of symmetry, the matingsurface being symmetrical about the respective second plane of symmetry,each said mating surface defining a convex polygon in a planeperpendicular to both its respective first plane of symmetry and itsrespective second plane of symmetry, said respective complementarymating surfaces being in an aligned configuration opposing each other inwhich said first planes of symmetry and said second planes of symmetryare substantially coincident during recharging; and wherein saidportable electrical device is placed upon said charging device by auser, said portable electrical device aligning its mating surface withrespect to the mating surface of the charging device automatically usinga gravitational force.
 2. The apparatus of claim 1, wherein said convexpolygon is a regular polygon.
 3. The apparatus of claim 2, wherein saidconvex polygon is a square.
 4. The apparatus of claim 1, wherein eachsaid mating surface defines a respective set of line segments in saidfirst plane of symmetry and in said second plane of symmetry.
 5. Theapparatus of claim 1, wherein the mating surface of said charging deviceis an upwardly facing concave surface and the mating surface of saidrechargeable device is a downwardly facing convex surface, saidgravitational force causing said rechargeable device to sink to thebottom of said concave surface of said rechargeable device toautomatically align said surfaces.
 6. The apparatus of claim 1, whereinthe mating surface of said at least one device comprises a set ofelectrical contacts for mating with contacts of the other mating surfaceof said complementary mating surfaces to transmit electrical current forrecharging said portable electrical device.
 7. The apparatus of claim 1,said at least one device further comprising a magnet for providing aforce to automatically align said mating surfaces with respect to eachother.
 8. The apparatus of claim 1, wherein said portable electricaldevice comprises a digital music player.
 9. An apparatus, comprising: atleast one device from a set of devices consisting of: (a) a portableelectrical device capable of storing electrical energy and requiringperiodic recharging, and (b) a charging device for supplying electricalenergy to said portable electrical device during recharging thereof;wherein said portable electrical device and said charging devicecomprise respective complementary mating surfaces which transmitelectrical energy from said charging device to said portable electricaldevice during recharging of said portable electrical device, each saidmating surface having a respective first plane of symmetry bisecting themating surface, the mating surface being symmetrical about therespective first plane of symmetry, and a respective second plane ofsymmetry bisecting the mating surface and perpendicular to therespective first plane of symmetry, the mating surface being symmetricalabout the respective second plane of symmetry, each said mating surfacedefining a convex polygon in a plane perpendicular to both itsrespective first plane of symmetry and its respective second plane ofsymmetry, said respective complementary mating surfaces being in analigned configuration opposing each other in which said first planes ofsymmetry and said second planes of symmetry are substantially coincidentduring recharging; and wherein said mating surfaces are aligned in afirst configuration and in a second configuration, said secondconfiguration being a configuration in which the mating surface of saidportable electrical device is rotated from the first configuration abouta central axis with respect to the mating surface of said chargingdevice, said central axis being the intersection of the first plane ofsymmetry of said mating surface of said portable electrical device andthe second plane of symmetry of said mating surface of said portableelectrical device.
 10. The apparatus of claim 9, wherein said convexpolygon is a regular polygon.
 11. The apparatus of claim 10, whereinsaid convex polygon is a square.
 12. The apparatus of claim 9, whereineach said mating surface defines a respective set of line segments insaid first plane of symmetry and in said second plane of symmetry. 13.The apparatus of claim 9, wherein complementary mating surfaces arealigned in N configurations, where N is the number of sides of saidregular polygon, each said configuration being a configuration in whichthe mating surface of said portable electrical device is rotated fromthe first configuration about a central axis with respect to the matingsurface of said charging device M*180/N degrees, where M is an integer,said central axis being the intersection of the first plane of symmetryof said mating surface of said portable electrical device and the secondplane of symmetry of said mating surface of said portable electricaldevice.
 14. The apparatus of claim 9, wherein said complementary matingsurfaces are shaped to automatically align said surfaces with respect toeach other using a gravitational force.
 15. The apparatus of claim 9,wherein the mating surface of said charging device is an upwardly facingconcave surface and the mating surface of said rechargeable device is adownwardly facing convex surface, said gravitational force causing saidrechargeable device to sink to the bottom of said concave surface ofsaid rechargeable device to a position in which said vertical axes aresubstantially coincident.
 16. The apparatus of claim 9, wherein themating surface of said at least one device comprises a set of electricalcontacts for mating with contacts of the other mating surface of saidcomplementary mating surfaces to transmit electrical current forrecharging said portable electrical device.
 17. The apparatus of claim9, said at least one device further comprising a magnet for providing aforce to automatically align said mating surfaces with respect to eachother.
 18. The apparatus of claim 9, wherein said portable electricaldevice comprises a digital music player.